Direct-current triboelectric nanogenerator based on electrostatic breakdown effect

With the rapid development of the Internet of Things (IoTs) era, higher demands are put forward for the power supply system to support the unimaginable complex distributed arrays of electronics and sensors, which is a great challenge to traditional concentrated power supply system. The distributed power supply system is a potential approach to solve this problem, where triboelectric nanogenerator (TENG) represents a core group of technologies supporting the distributed power supply system. A conventional TENG relies on triboelectrification and electrostatic induction and it usually gives an alternative-current (AC) output. However, instead of using the displacement current driven TENG that produces an AC current across an external load, we use the electrostatic breakdown effect across an interface for realizing a direct-current TENG (DC-TENG). This paper gives a comprehensive review on fundamentals of DC-TENG. Compared with conventional AC-TENG, DC-TENG has high charge density and can drive electronics directly. The internal mechanism, performance limitation factors and theoretical model of DC-TENG are presented in details. The enhancement methods of its output performance, containing the optimizations of triboelectrification process, electrostatic breakdown process and device structure, are summarized and discussed. Additionally, the potential applications of DC-TENG are briefly reviewed. Besides its current advancement, the challenge and future growth of DC-TENG are also forecasted and outlined. Through this review, we hope to establish a guideline for the design strategies of DC-TENG and illustrate the future exploration of new optimization and application of DC-TENG.